The present invention relates to a process for stabilizing an aqueous solution of an acrylic or methacrylic hydrazide polymer.
It is known that a water-soluble polymer containing acrylic or methacrylic hydrazide units in its polymer chain is available as a polymeric cross-linking agent because of the high activity caused by hydrazide group, also as a sizing agent, a strengthening agent and a fire retardant for paper because of showing behavior as a cationic polymer in an acidic aqueous solution, and as a sequestering agent because of forming chelate compounds with various heavy metal ions.
However, an aqueous solution of such an acrylic or methacrylic hydrazide polymer is very unstable, and the gelation of the aqueous solution takes place in a short period of time and the polymer becomes insoluble in water. Therefore, since the storage of the aqueous solution is difficult, the aqueous solution must be used immediately after the preparation. For such a reason, the acrylic or methacrylic hydrazide polymers have not been effectively employed, despite that the useful properties as mentioned above are known.